Estimating method for a rotor position of a motor and estimating device for the same

ABSTRACT

An estimating method for a rotor position of a motor and an estimating device for the same are disclosed herein. The estimating method includes injecting a first high frequency signal to the motor at a first estimating angle, generating a first sensing signal of the motor in a period when the first high frequency signal is injected to the motor, injecting a second high frequency signal to the motor at a second estimating angle, generating a second sensing signal of the motor in a period when the second high frequency signal is injected to the motor, determining a quadrant of an operating angle according to the first sensing signal and the second sensing signal, and acquiring the rotor position according to the first sensing signal, the second sensing signal, and the quadrant of the operating angle.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number102128403, filed Aug. 8, 2013, which is herein incorporated byreference.

BACKGROUND

1. Field of Invention

The present disclosure relates to an estimating method for a rotorposition of a motor and an estimating device for the same.

2. Description of Related Art

With advances in technology, motors are widely used in our daily lives.For example, motors are used in hard disks, air conditioners, cranes,and so on.

A permanent magnet synchronous motor (PMSM) includes a plurality ofstators and a rotor. The stators can be fabricated by wires, and aredisposed around the rotor. The rotation of the rotor can be controlledby controlling currents applied to the stators.

In a control (or an activation) of the PMSM, it is necessary to firstestimate the rotor position of the PMSM, after which the currents can beprovided to the stators to rotate the rotor according to the estimatedrotor position of the PMSM. If there is a large deviation between theestimated rotor position and an actual rotor position, the rotor mayrotate in the wrong rotational direction or control of the PMSM mayfail, resulting in operational instability of the PMSM.

Thus, an estimating method for accurately estimating the rotor positionof a motor is desired.

SUMMARY

One aspect of the present invention is directed to an estimating methodfor a rotor position of a motor. In accordance with one embodiment ofthe present invention, the estimating method includes injecting a firsthigh frequency signal to the motor at a first estimating angle,generating a first sensing signal of the motor in a period when thefirst high frequency signal is injected to the motor, injecting a secondhigh frequency signal to the motor at a second estimating angle,generating a second sensing signal of the motor in a period when thesecond high frequency signal is injected to the motor, determining aquadrant of an operating angle according to the first sensing signal andthe second sensing signal, and acquiring the rotor position according tothe first sensing signal, the second sensing signal, and the quadrant ofthe operating angle. The second estimating angle is different from thefirst estimating angle. The operating angle is twice as large as anangle difference between the first estimating angle and the rotorposition.

Another aspect of the present invention is directed to an estimatingdevice for estimating a rotor position of a motor. In accordance withone embodiment of the present invention, the estimating device iselectrically connected to the motor. The estimating device includes ahigh frequency signal injection module, a sensing module, and acalculating module. The high frequency signal injection module isconfigured to inject a first high frequency signal to the motor at afirst estimating angle, and inject a second high frequency signal to themotor at a second estimating angle. The second estimating angle isdifferent from the first estimating angle. The sensing module isconfigured to generate a first sensing signal of the motor in a periodwhen the first high frequency signal is injected to the motor, andgenerate a second sensing signal of the motor in a period when thesecond high frequency signal is injected to the motor. The calculatingmodule is configured to determine a quadrant of an operating angleaccording to the first sensing signal and the second sensing signal, andacquire the rotor position according to the first sensing signal, thesecond sensing signal, and the quadrant of the operating angle. Theoperating angle is twice as large as an angle difference between thefirst estimating angle and the rotor position.

Thus, through application of one of the embodiments mentioned above, theestimating device can rapidly determine the quadrant of the operatingangle according to the first sensing signal and the second sensingsignal, so as to acquire the rotor position. Through such operation, thestability of the motor can be effectively increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1 is a schematic diagram of an estimating device in accordance withone embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a high frequency signal injectionmodule, a sensing module, and a calculating module in the estimatingdevice in accordance with one embodiment of the present disclosure; and

FIG. 3 is a flow chart of an estimating method in accordance with oneembodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to attain a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically shown in order to simplify the drawing.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the embodiments.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Moreover, “electrically connect” or“connect” can further refer to the interoperation or interaction betweentwo or more elements.

Any element in a claim that does not explicitly state “means for”performing a specified function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. §112, 6th paragraph. In particular, the use of“step of” in the claims herein is not intended to invoke the provisionsof 35 U.S.C. §112, 6th paragraph.

One aspect of the present invention is an estimating device forestimating a rotor position of a motor. To facilitate the description tofollow, reference is made to FIG. 1 and FIG. 2, in which FIG. 1 is aschematic diagram of an estimating device 100 in accordance with oneembodiment of the present disclosure, and FIG. 2 is a schematic diagramof a high frequency signal injection module 110, a sensing module 120,and a calculating module 130 in the estimating device 100 in accordancewith one embodiment of the present disclosure.

The estimating device 100 is electrically connected to a motor 10 and aninverter 20, and is configured to estimate a rotor position (or a rotorangle) 0 of a rotor of the motor 10. The estimating device 100 can berealized by a computer or a circuit assembly. The motor 10 can be apermanent magnet synchronous motor (PMSM). The inverter 20 can berealized by a plurality of transistors.

In this embodiment, the estimating device 100 includes the highfrequency signal injection module 110, the sensing module 120, thecalculating module 130, and a determining module 140. The high frequencysignal injection module 110, the sensing module 120, the calculatingmodule 130, the determining module 140, the inverter 20, and the motor10 can be electrically connected to each other. Each of the highfrequency signal injection module 110, the sensing module 120, thecalculating module 130, and the determining module 140 can be realizedby software or hardware.

It should be noted that the ways in which the estimating device 100, themotor 10, the inverter 20, the high frequency signal injection module110, the sensing module 120, the calculating module 130, and thedetermining module 140 are realized are not limited by the embodimentsdescribed above. In addition, the connections among these devices andmodules are not limited by the embodiments described above. Anyconfiguration of these devices and interconnections thereamong thatwould enable the estimating device 100 to practice the technicalfeatures described below can be used herein.

In this embodiment, the high frequency signal injection module 110 isconfigured to inject a first high frequency signal f₁₁ to the motor 10at a first estimating angle {circumflex over (θ)}₁ through the inverter20, as illustrated in FIG. 2. In one embodiment, the high frequencysignal injection module 110 can provide first space vector pulse widthmodulation (SVPWM) signals v_(α3c), v_(β1c), to the inverter 20 to makethe inverter 20 generate stator currents i_(U1), i_(V1), i_(W1), andprovide the stator currents i_(U1), i_(V1), i_(W1), to the motor 20. Inaddition, the high frequency signal injection module 110 is furtherconfigured to inject a second high frequency signal f₁₂ to the motor 10at a second estimating angle (or a disturbing angle) {circumflex over(θ)}₂ through the inverter 20. In one embodiment, the high frequencysignal injection module 110 can provide second SVPWM signals v_(α2c),v_(β2c), to the inverter 20 to make the inverter 20 generate statorcurrents i_(U2), i_(V2), i_(W2), and provide the stator currents i_(U2),i_(V2), i_(W2), to the motor 20. In this embodiment, the secondestimating angle {circumflex over (θ)}₂ is different from the firstestimating angle {circumflex over (θ)}₁. Moreover, in one embodiment,there is a tiny disturbing difference between the first estimating angle{circumflex over (θ)}₁ and the second estimating angle {circumflex over(θ)}₂.

The sensing module 120 is configured to sense the stator currentsi_(U2), i_(V1), i_(W1), on the motor 10 and generate a first sensingsignal (e.g., at least one of response currents î_(d1), î_(q1), of themotor 10) according to the stator currents i_(U1), i_(V1), i_(W1), inthe period when the high frequency signal injection module 110 injectsthe first high frequency signal f₁₁ to the motor 10. In addition, thesensing module 120 is further configured to sense the stator currentsi_(U2), i_(V2), i_(W2) on the motor 10 and generate a second sensingsignal (e.g., at least one of response currents î_(d2), î_(q2) of themotor 10) according to the stator currents i_(U2), i_(V2), i_(W2), inthe period when the high frequency signal injection module 110 injectsthe second high frequency signal f₁₂ to the motor 10.

The calculating module 130 is configured to acquire values of a sinefunction of an operating angle φ and a cosine function of the operatingangle φ according to the first sensing signal and the second sensingsignal, and determine a quadrant of the operating angle φ according towhether each of the values of the sine function of the operating angle φand the cosine function of the operating angle φ is a positive number ora negative number. In this embodiment, the operating angle φ correspondsto an angle difference Δθ₁ between the first estimating angle{circumflex over (φ)}₁ and the rotor position θ (e.g., Δθ₁=θ−{circumflexover (θ)}₁). In one embodiment, the operating angle is twice as large asthe angle difference Δθ₁ between the first estimating angle {circumflexover (θ)}₁ and the rotor position θ (e.g., φ=2×Δθ₁).

Subsequently, the calculating module 130 is configured to calculate thevalue of the operating angle φ through an inverse trigonometric functionaccording to the values of the sine function of the operating angle φand the cosine function of the operating angle φ. Next, the calculatingmodule 130 is configured to calculate a value of the rotor position θaccording to the operating angle φ, the quadrant of the operating angleφ, and the first estimating angle φ.

After the value of the rotor position θ is calculated, the determiningmodule 140 is configured to determine a direction of a magnetic northpole of the rotor of the motor 10 using a pulse injection method. Hence,the rotor position θ of the motor 10 can be ascertained.

To better explain the estimating device 100, one exemplary embodimentthereof is described in the following paragraphs. However, the inventionis not limited by the exemplary embodiment described below.

In this exemplary embodiment, in a period when the high frequency signalinjection module 110 injects the first high frequency signal f₁₁ with avalue U_(i) cos ω_(i)t (U_(i) and ω_(i) can be regarded as constantsherein) to a d-axis of the motor 10 at the first estimating angle{circumflex over (θ)}₁, the sensing module 120 can sense the statorcurrents i_(U1), i_(V1), i_(W1), on the motor 10, and accordinglygenerate the response current î_(d1) on the d-axis of the motor 10 andthe response current î_(q1) on the q-axis of the motor 10. Values of theresponse currents î_(d1), î_(q1) can be presented as the followingequation:

$\begin{matrix}{\begin{bmatrix}{\hat{i}}_{d\; 1} \\{\hat{i}}_{q\; 1}\end{bmatrix} = \begin{bmatrix}{\frac{U_{i}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\left( {L - {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}\; 1}} \right)} \\{{\frac{{- U_{i}}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}\; 1}\;}\end{bmatrix}} & {{Eq}\mspace{14mu} (1)}\end{matrix}$

In Eq(1), L and ΔL can be regarded as constants herein.

The calculating module 130 samples the response current î_(q1) and mixes(or multiplies) the response current î_(q1) with a high frequencycarrier f_(c) having a value sin ω_(i)t to generate a first mixingsignal m1. Subsequently, the calculating module 130 low-pass filters thefirst mixing signal m1 to acquire a first calculating value f_(Δθ1). Thefirst calculating value f_(Δθ1) can be presented by the followingequation:

$\begin{matrix}{{f_{{\Delta\theta}\; 1} = {k\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}\; 1}},{k = {\frac{- U_{i}}{2\; {\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}}\Delta \; L}}} & {{Eq}\mspace{14mu} (2)}\end{matrix}$

Through the equation above, the value of the sine function of the angle2Δθ1 can be acquired, that is, the value of the sine function of theoperating angle φ can be acquired.

Additionally, when Eq(2) is differentiated by the angle {circumflex over(θ)}₁, the cosine function of the angle 2Δθ1 can be acquired. Theequation can be presented as follows:

$\begin{matrix}{\frac{{df}_{{\Delta\theta}\; 1}}{d\; {\hat{\theta}}_{1}} = {{k\mspace{14mu} \cos \mspace{14mu} 2\; {{\Delta\theta}_{1} \cdot \frac{d\left( {2\; {\Delta\theta}_{1}} \right)}{d\; {\hat{\theta}}_{1}}}} = {k\mspace{14mu} \cos \mspace{14mu} 2\; {{\Delta\theta}_{1} \cdot \left( {- 2} \right)}}}} & {{Eq}\mspace{14mu} (3)}\end{matrix}$

To solve the equation above, the high frequency signal injection module110 injects a second high frequency signal f₁₂ with a value U_(i) cosω_(i)t to the d-axis of the motor 10 at the second estimating angle{circumflex over (θ)}₂. The sensing module 120 senses the statorcurrents i_(U2), i_(V2), i_(W2), on the motor 10, and accordinglygenerates the response current î_(d2), on the d-axis of the motor 10 andthe response current î_(q2) on the q-axis of the motor 10. Subsequently,the calculating module 130 samples the response current î_(q2) and mixes(or multiplies) the response current î_(q2) with the high frequencycarrier f, having the value sin, wt to generate a second mixing signalm2. Subsequently, the calculating module 130 low-pass filters the secondmixing signal m2 to acquire a second calculating value f_(Δθ2). In astate where there is a tiny difference between the first estimatingangle {circumflex over (θ)}₁ and the second estimating angle {circumflexover (0)}₂ (e.g., {circumflex over (θ)}₂−{circumflex over (θ)}₁=dθ),Eq(3) presented above can be solved by the first estimating angle{circumflex over (θ)}₁, the second estimating angle {circumflex over(θ)}₂, the first calculating value f_(Δθ1), and the second calculatingvalue f_(Δθ2), such that the value of the cosine function of the angle2Δθ1 (that is, the cosine function of the operating angle φ) can beacquired. The equation can be presented as follows:

$\begin{matrix}{\frac{f_{{\Delta\theta}\; 2} - f_{{\Delta\theta}\; 1}}{{\hat{\theta}}_{2} - {\hat{\theta}}_{1}} = {\frac{{df}_{{\Delta\theta}\; 1}}{d\; {\hat{\theta}}_{1}} = {{k\mspace{14mu} \cos \mspace{14mu} 2\; {{\Delta\theta}_{1} \cdot \frac{d\left( {2\; {\Delta\theta}_{1}} \right)}{d\; {\hat{\theta}}_{1}}}} = {k\mspace{14mu} \cos \mspace{14mu} 2{{\Delta\theta}_{1} \cdot \left( {- 2} \right)}}}}} & {{Eq}\mspace{14mu} (4)}\end{matrix}$

After the values of the sine function and the cosine function of theangle 2Δθ1 are acquired, the calculating module 130 determines thequadrant of the angle 2Δθ1 accordingly. For example, when both of thevalues of k sin 2Δθ₁ and k cos 2Δθ₁ are positive numbers, the angle 2Δθ1is in the first quadrant. When the value of k sin 2Δθ₁ is a positivenumber, and the value of k cos 2Δθ₁ is a negative number, the angle 2Δθ1is in the second quadrant.

Additionally, after the values of the sine function and the cosinefunction of the angle 2Δθ1 are acquired, the calculating module 130calculates the angle difference Δθ₁ between the first estimating angle{circumflex over (θ)}₁ and the rotor position θ through the inversetrigonometric function. The equation can be presented as follows:

$\begin{matrix}{{2\; {\Delta\theta}_{1}} = {\tan^{- 1}\mspace{14mu} \left( {{f_{{\Delta\theta}\; 1} \div \left( \frac{{df}_{{\Delta\theta}\; 1}}{d\; {\hat{\theta}}_{1}} \right)} \times \left( {- 2} \right)} \right)}} & {{Eq}\mspace{14mu} (5)}\end{matrix}$

Through such operation, the calculating module 130 can calculate therotor position θ according to the angle difference Δθ₁ between the firstestimating angle {circumflex over (θ)}₁ and the rotor position θ (sinceΔθ₁=θ={circumflex over (θ)}₁, and both of Δθ₁ and {circumflex over (θ)}₁are known).

It should be noted that although the first high frequency signal f₁₁ andthe second high frequency signal f₁₂ are injected to the d-axis of themotor 10, and the calculating module 130 samples the response currentsî_(q1), î_(q2) on the q-axis of the motor 10, so as to generate thefirst calculating value f_(Δθ1) and the second calculating value f_(Δθ2)in the exemplary embodiment above, the invention is not limited by suchoperation.

In one embodiment, in the period when a high frequency signal with avalue U₁ cos ω_(i)t is injected to the q-axis of the motor 10, theresponse currents î_(d), î_(q) respectively on the d-axis and q-axis canbe presented as follows:

$\begin{matrix}{\begin{bmatrix}{\hat{i}}_{d\;} \\{\hat{i}}_{q\;}\end{bmatrix} = \begin{bmatrix}{\frac{{- U_{i}}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}} \\{{\frac{U_{i}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\left( {L + {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}}} \right)}\;}\end{bmatrix}} & {{Eq}\mspace{14mu} (6)}\end{matrix}$

In the equation above, Δθ=θ−{circumflex over (θ)}.

In this embodiment, the calculating module 130 can sample the responsecurrent î_(d) on the d-axis of the motor 10, mix the response currentî_(d) with the high frequency carrier f_(c) having the value sin ω_(i)tto generate a mixing signal, and low-pass filter the mixing signal toacquire a calculating value f_(Δθ)=k sin 2Δθ. Therefore, in thisembodiment, through operations similar to those in the exemplaryembodiment above, the values of the sine function and the cosinefunction of the angle 2Δθ1 can be acquired, and the rotor position θ canbe accordingly calculated. A description in this regard will not berepeated herein.

In one embodiment, in the period when a high frequency signal with avalue U_(i) cos ω_(i)t is injected to the d-axis and the q-axis of themotor 10 at the same time, the response currents î_(d), î_(q),respectively on the d-axis and q-axis can be presented as follows:

$\begin{matrix}{\begin{bmatrix}{\hat{i}}_{d\;} \\{\hat{i}}_{q\;}\end{bmatrix} = \begin{bmatrix}{\frac{U_{i}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\left( {L - {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}} - {\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}}} \right)} \\{{\frac{U_{i}\mspace{14mu} \sin \mspace{14mu} \omega_{i}t}{\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}\left( {L + {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}} - {\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2{\Delta\theta}}} \right)}\;}\end{bmatrix}} & {{Eq}\mspace{14mu} (7)}\end{matrix}$

In this embodiment, the calculating module 130 can sample the responsecurrent î_(d) on the d-axis of the motor 10, mix the response currentî_(d) with the high frequency carrier f_(c) having the value sin ω_(i)tto generate a mixing signal, and low-pass filter the mixing signal toacquire a calculating value f_(Δθ-d). In addition, the calculatingmodule 130 can sample the response current î_(q) on the q-axis of themotor 10, mix the response current î_(q) with the high frequency carrierf_(c) having the value sin ω_(i)t to generate another mixing signal, andlow-pass filter the another mixing signal to acquire a calculating valuef_(Δθ-q), The calculating values f_(Δθ-d), f_(Δθ-q) can be presented asfollows:

$\begin{matrix}{\begin{bmatrix}f_{{\Delta\theta} - d} \\f_{{\Delta\theta} - q}\end{bmatrix} = \begin{bmatrix}{\frac{U_{i}}{2\; {\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}}\left( {L - {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}} - {\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}}} \right)} \\{\frac{U_{i}}{2\; {\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}}\left( {L + {\Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}} - {\Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; \Delta \; \theta}} \right)}\end{bmatrix}} & {{Eq}\mspace{14mu} (8)}\end{matrix}$

An equation Eq(9) can be derived using equation Eq(8). The equationEq(9) is presented as follows:

$\begin{matrix}{\begin{bmatrix}{f_{{\Delta\theta} - q} - f_{{\Delta\theta} - d}} \\{\frac{{df}_{{\Delta\theta} - d}}{d\; \hat{\theta}} - \frac{{df}_{{\Delta\theta} - q}}{d\; \hat{\theta}}}\end{bmatrix} = \begin{bmatrix}{\frac{U_{i\;}}{2\; {\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}}\left( {2\; \Delta \; L\mspace{14mu} \cos \mspace{14mu} 2\; {\Delta\theta}} \right)} \\{\frac{U_{i}}{2\; {\omega_{i}\left( {L^{2} - {\Delta \; L^{2}}} \right)}}{\left( {2\; \Delta \; L\mspace{14mu} \sin \mspace{14mu} 2\; {\Delta\theta}} \right) \cdot \left( {- 2} \right)}}\end{bmatrix}} & {{Eq}\mspace{14mu} (9)}\end{matrix}$

Therefore, in this embodiment, through operations similar to those inthe exemplary embodiment above, the values of the sine function and thecosine function of the angle 2Δθ1 can be acquired using Eq(9), and therotor position θ can be accordingly calculated. A description in thisregard will not be repeated herein.

Through such operation, by providing the first high frequency signal f₁₁and the second high frequency signal f₁₂ to the motor 10 at the firstestimating angle {circumflex over (θ)}₁ and the second estimating angle{circumflex over (θ)}₂ respectively, the estimating device 100 canrapidly determine the quadrant of the operating angle φ, so as torapidly calculate the value of the operating angle φ to acquire therotor position θ. Through application of the estimating device 100, thecontrol of the motor 10 can be more stable.

In the following paragraphs, more details of the high frequency signalinjection module 110, the sensing module 120, and the calculating module130 are provided. However, the invention is not limited by theembodiments below.

As mentioned above, the high frequency signal injection module 110 isconfigured to inject the first high frequency signal f₁₁ to the motor 10at the first estimating angle {circumflex over (θ)}₁ through theinverter 20, and inject the second high frequency signal f₁₂ to themotor 10 at the second estimating angle {circumflex over (θ)}₂ throughthe inverter 20.

To achieve such a function, in this embodiment, the high frequencysignal injection module 110 includes an injection signal generating unit112, an adder A1, an inverse Park transformation unit 114, and a pulsewidth modulation (PWM) signal generating unit 116 (e.g., a space vectorpulse width modulation (SVPWM) signal generating unit). The injectionsignal generating unit 112 is electrically connected to a q-axis inputend of the inverse Park transformation unit 114 and the adder A1. Theadder A1 is electrically connected to a d-axis input end of the inversePark transformation unit 114. The inverse Park transformation unit 114is electrically connected to the PWM signal generating unit 116. The PWMsignal generating unit 116 is electrically connected to the inverter 20.

The injection signal generating unit 112 is configured to separatelygenerate the first high frequency signal f₁₁ and the second highfrequency signal f₁₂, a d-axis reference signal {circumflex over(v)}_(d,ref), a q-axis reference signal {circumflex over (v)}_(q,ref),the first estimating angle {circumflex over (θ)}₁, and the secondestimating angle {circumflex over (θ)}₂. Both of the values of the firsthigh frequency signal f₁₁ and the second high frequency signal f₁₂ are,for example, U_(i) cos ω_(i)t. Both of the values of the d-axisreference signal {circumflex over (v)}_(d,ref) and the q-axis referencesignal {circumflex over (v)}_(q,ref) are, for example, zero. The valueof the first estimating angle {circumflex over (θ)}₁ is, for example,zero. The value of the second estimating angle {circumflex over (θ)}₂is, for example, d{circumflex over (θ)}₁. Additionally, both of thefirst high frequency signal f₁₁ and the second high frequency signal f₁₂are voltage signals.

The adder A1 is configured to receive the first high frequency signalf₁₁, the second high frequency signal f₁₂, and the d-axis referencesignal {circumflex over (v)}_(d,ref), separately add the first highfrequency signal f₁₁ with the d-axis reference signal {circumflex over(v)}_(d,ref) and the second high frequency signal f₁₂ with the d-axisreference signal {circumflex over (v)}_(d,ref), and transmit the addedsignals to the d-axis input end of the inverse Park transformation unit114.

In a period when receiving the first estimating angle {circumflex over(θ)}₁, the inverse Park transformation unit 114 is configured togenerate first converting signals v_(α1), v_(β1) according to the firstestimating angle {circumflex over (θ)}₁, the first high frequency signalf₁₁, the d-axis reference signal {circumflex over (v)}_(d,ref), and theq-axis reference signal {circumflex over (v)}_(q,ref). Additionally, ina period when receiving the second estimating angle {circumflex over(θ)}₂, the inverse Park transformation unit 114 is configured togenerate second converting signals v_(α2), v_(β2) according to thesecond estimating angle {circumflex over (θ)}₂, the second highfrequency signal f₁₂, the d-axis reference signal {circumflex over(v)}_(d,ref), and the q-axis reference signal {circumflex over(v)}_(q,ref).

When receiving the first converting signal v_(α1), v_(β1) (e.g., in theperiod when the inverse Park transformation unit 114 receives the firstestimating angle {circumflex over (θ)}₁), the PWM signal generating unit116 is configured to provide first SVPWM signals v_(α1c), v_(β1c)corresponding to the first frequency signal f₁₁ to the inverter 20. Whenreceiving the second converting signal v_(α2), v_(β2) (e.g., in theperiod when the inverse Park transformation unit 114 receives the secondestimating angle {circumflex over (θ)}₂), the PWM signal generating unit116 is configured to provide second SVPWM signals v_(α2c), v_(β2c)corresponding to the second frequency signal f₁₂ to the inverter 20.

Through such a configuration, the high frequency signal injection module110 can inject the first high frequency signal f₁₁ to the motor 10 atthe first estimating angle {circumflex over (θ)}₁ through the inverter20, and inject the second high frequency signal f₁₂ to the motor 10 atthe second estimating angle {circumflex over (θ)}₂ through the inverter20.

It should be noted that, in the embodiment above, since the adder A1 iselectrically connected to the d-axis input end of the inverse Parktransformation unit 114, the first high frequency signal f₁₁ and thesecond high frequency signal f₁₂ are injected to the d-axis of the motor10. However, as mentioned in the paragraphs above, the first highfrequency signal f₁₁ and the second high frequency signal f₁₂ can beinjected to the q-axis of the motor 10, or injected to the d-axis andq-axis of the motor 10. Thus, the invention is not limited by theembodiment described above.

As mentioned above, the sensing module 120 is configured to sense thestator currents i_(U1), i_(V1), i_(W1), i_(U2), i_(V2), i_(W2) on themotor 10, and accordingly generate the response currents î_(q1), î_(q2)on the d-axis of the motor 10 and the response currents î_(q1), î_(q2)on the q-axis of the motor 10. The first sensing signal is at least oneof the response currents î_(d1), î_(q1), and the second sensing signalis at least one of the response currents î_(d2), î_(q2).

In this embodiment, the sensing module 120 includes a Clarketransformation unit 122 and a Park transformation unit 124. The Clarketransformation unit 122 and the Park transformation unit 124 areelectrically connected to each other.

The Clarke transformation unit 122 is configured to receive the statorcurrents i_(U1), i_(V1), i_(W1) of the motor 10, and generate convertingsignals i_(α1), i_(β1) according to the stator currents i_(U1), i_(V1),i_(W1). Additionally, the Clarke transformation unit 122 is configuredto receive the stator currents i_(U2), i_(V2), i_(W2) of the motor 10,and generate converting signals i_(α2), i_(β2) according to the statorcurrents i_(U2), i_(V2), i_(W2).

The Park transformation unit 124 is configured to receive the convertingsignals i_(α1), i_(β1), and generate response currents î_(d1), î_(q1),according to the converting signals i_(α1), i_(β1). Additionally, thePark transformation unit 124 is configured to receive the convertingsignals i_(α2), i_(β2), and generate response currents î_(d2), î_(q2)according to the converting signals i_(α2), i_(β2).

Through such a configuration, in the period when the high frequencysignal injection module 110 injects the first high frequency signal f₁₁to the motor 10, the sensing module 120 can accordingly generate theresponse current î_(d1) on the d-axis of the motor 10 and the responsecurrents î_(q1) on the q-axis of the motor 10. Additionally, in theperiod when the high frequency signal injection module 110 injects thesecond high frequency signal f₁₂ to the motor 10, the sensing module 120can accordingly generate the response current î_(d2) on the d-axis ofthe motor 10 and the response currents î_(q2) on the q-axis of the motor10.

As mentioned above, the calculating module 130 is configured tocalculate the operating angle φ and the rotor position θ according tothe first sensing signal (e.g., at least one of response currentsî_(d2), î_(q2)) and the second sensing signal (e.g., at least one ofresponse currents î_(d2), î_(q2)).

In this embodiment, the calculating module 130 includes a mixer M1, afiltering unit 132, a first calculating unit 134, a quadrant determiningunit 136, a second calculating unit 138, a mixer M2, and an adder A2.The mixer M1 is electrically connected to a q-axis output end of thePark transformation unit 124 and the filtering unit 132. The filteringunit 132 is electrically connected to the first calculating unit 134 andthe quadrant determining unit 136. The first calculating unit 134 iselectrically connected to the quadrant determining unit 136. Thequadrant determining unit 136 is electrically connected to the secondcalculating unit 138. The second calculating unit 138 is electricallyconnected to the mixer M2. The mixer M2 is electrically connected to theadder A2.

In this embodiment, the mixer M1 is configured to receive the responsecurrent î_(q1) (e.g., the first sensing signal in this embodiment) andthe response current î_(q2) (e.g., the second sensing signal in thisembodiment) from the q-axis output end of the Park transformation unit124. Additionally, the mixer M1 is configured to receive the highfrequency carrier f_(c) (e.g., the high frequency carrier f_(c) has avalue sin ω_(i)t). The mixer M1 is configured to mix the first sensingsignal î_(q1) with the high frequency carrier f_(c) to generate thefirst mixing signal m1, and mix the second sensing signal î_(q2) withthe high frequency carrier f_(c) to generate the second mixing signalm2.

The filtering unit 132 is configured to sequentially receive the firstmixing signal m1 and the second mixing signal m2, and sequentiallylow-pass filter the first mixing signal m1 and the second mixing signalm2 to respectively generate the first calculating value f_(Δθ1) and thesecond calculating value f_(Δθ2). The value of the sine function of theoperating angle φ can be acquired according to the first calculatingvalue f_(Δθ1).

The first calculating unit 134 is configured to acquire the value of thecosine function of the operating angle φ according to the firstcalculating value f_(Δθ1), the second calculating value f_(Δθ2), thefirst estimating angle {circumflex over (θ)}₁ and the second estimatingangle {circumflex over (θ)}₂.

Subsequently, the quadrant determining unit 136 is configured todetermine the quadrant of the operating angle φ according to the valuesof the sine function and the cosine function of the operating angle θ.

The second calculating unit 138 is configured to calculate the value ofthe operating angle φ through the inverse trigonometric functionaccording to the values of the sine function and the cosine function ofthe operating angle φ.

Subsequently, the mixer M2 is configured to generate the angledifference Δθ₁ between the first estimating angle {circumflex over (θ)}₁and the rotor position θ according to the operating angle φ.

Next, the adder A2 is configured to generate the rotor position θaccording to the angle difference Δθ₁ between the first estimating angle{circumflex over (θ)}₁ and the rotor position θ.

It should be noted that details of the units in this embodiment can beascertained by referring to the exemplary embodiment mentioned above,and a description in this regard will not be repeated herein.

Through such a configuration, the calculating module 130 can calculatethe operating angle φ and the rotor position θ according to the firstsensing signal (e.g., response current î_(q1)) and the second sensingsignal (e.g., response current î_(q2)).

In addition, since the mixer M1 samples the response currents î_(q1),î_(q2) on the q-axis output end of the Park transformation unit 124, inthe embodiment above, the response current î_(q1) serves as the firstsensing signal, the response current î_(q2) serves as the second sensingsignal, and the calculating module 130 calculates the operating angle φand the rotor position θ according to the response currents î_(q1),î_(q2). However, as mentioned above, the calculating module 130 cansample the response currents î_(d1), î_(d2) on the d-axis output end ofthe Park transformation unit 124, or sample the response currentsî_(d1), î_(d2), î_(q1), î_(q2) on the d-axis output end and the q-axisoutput end of the Park transformation unit 124. That is, in someembodiments, the response currents î_(d1), î_(d2) can serve as the firstsensing signal and the second sensing signal respectively, or theresponse currents î_(d1), î_(q1) and î_(d2), î_(q2) can serve as thefirst sensing signal and the second sensing signal respectively. Theinvention is not limited in this regard by the embodiment describedabove.

Another aspect of the present invention is an estimating method for arotor position of a motor.

The estimating method can be applied to an estimating device having astructure that is the same as or similar to the structure shown in FIG.1 and FIG. 2. To simplify the description below, in the followingparagraphs, the embodiments shown in FIG. 1 and FIG. 2 will be used asan example to describe the estimating method according to embodiments ofthe present disclosure. However, the invention is not limited toapplication to the embodiments shown in FIG. 1 and FIG. 2.

In addition, it should be noted that, in the steps of the followingestimating method, no particular sequence is required unless otherwisespecified. Moreover, the following steps also may be performedsimultaneously or the execution times thereof may at least partiallyoverlap.

FIG. 3 is a flow chart of an estimating method 300 in accordance withone embodiment of the present disclosure. The estimating method 300includes the steps below.

In step S1, through the high frequency signal injection module 110 andthe inverter 20, the first high frequency signal f₁₁ is injected to themotor 10 at the first estimating angle {circumflex over (θ)}₁.

In step S2, through the sensing module 120, in the period when the firsthigh frequency signal f₁₁ is injected to the motor 10, the statorcurrents i_(U1), i_(V1), i_(W1), of the motor 10 are sensed, and thefirst sensing signal of the motor 10 is generated according to thestator currents i_(U1), i_(V1), i_(W1).

In step S3, through the high frequency signal injection module 110 andthe inverter 20, the second high frequency signal f₁₂ is injected to themotor 10 at the second estimating angle {circumflex over (θ)}₂. Thesecond estimating angle {circumflex over (θ)}₂ is different from thefirst estimating angle {circumflex over (θ)}₁.

In step S4, through the sensing module 120, in the period when thesecond high frequency signal f₁₂ is injected to the motor 10, the statorcurrents i_(U2), i_(V2), i_(W2) of the motor 10 are sensed, and thesecond sensing signal of the motor 10 is generated according to thestator currents i_(U2), i_(V2), i_(W2).

In step S5, through the calculating module 130, the values of the sinefunction and the cosine function of the operating angle φ are acquired,and the quadrant of the operating angle φ is determined according towhether each of the values of the sine function and the cosine functionof the operating angle φ is a positive number or a negative number. Theoperating angle φ corresponds to the angle difference Δθ₁ between thefirst estimating angle {circumflex over (θ)}₁ and the rotor position θ(e.g., Δθ₁=θ−{circumflex over (θ)}₁). In one embodiment, the operatingangle φ is twice as large as the angle difference Δθ₁ between the firstestimating angle {circumflex over (θ)}₁ and the rotor position θ (e.g.,φ=2×Δθ1).

In step S6, through the calculating module 130, the value of theoperating angle φ is calculated through the inverse trigonometricfunction according to the values of the sine function and the cosinefunction of the operating angle φ. Subsequently, the calculating module130 calculates the rotor position θ according to the operating angle φ,the quadrant of the operating angle φ, and the first estimating angle φ.

In step S7, through the determining module 140, the direction of themagnetic north pole of the rotor of the motor 10 is determined using thepulse injection method. Hence, the rotor position θ of the motor 10 canbe ascertained.

Through such operation, by providing the first high frequency signal f₁₁and the second high frequency signal f₁₂ to the motor 10 at the firstestimating angle {circumflex over (θ)}₁ and the second estimating angle{circumflex over (θ)}₂ respectively, the estimating device 100 canrapidly determine the quadrant of the operating angle φ, so as torapidly calculate the value of the operating angle φ to acquire thevalue of the rotor position θ. Through application of the estimatingdevice 100, the control of the motor 10 can be more stable.

In accordance with one embodiment, the first sensing signal is at leastone of the response current î_(d1) on the d-axis of the motor 10 and theresponse current î_(q1) on the q-axis of the motor 10. The secondsensing signal is at least one of the response current î_(d2) on thed-axis of the motor 10 and the response current î_(q2) on the q-axis ofthe motor 10.

In accordance with one embodiment, in step S1, the high frequency signalinjection module 110 injects the first high frequency signal f₁₁ to atleast one of the d-axis and the q-axis of the motor 10 at the firstestimating angle {circumflex over (θ)}₁.

In accordance with one embodiment, in step S3, the high frequency signalinjection module 110 injects the second high frequency signal f₁₂ to atleast one of the d-axis and the q-axis of the motor 10 at the secondestimating angle {circumflex over (θ)}₂. The first high frequency signalf₁₁ and the second high frequency signal f₁₂ are injected to the sameq-axis of the motor 10, the same d-axis of the motor 10, or both of theq-axis and the d-axis of the motor 10.

In accordance with one embodiment, in step S5, the calculating module130 mixes the first sensing signal with the high frequency carrier f_(c)to generate the first mixing signal m1, and low-pass filters the firstmixing signal m1 to acquire a first calculating value f_(Δθ1). Thecalculating module 130 acquires the value of the sine function of theoperating angle φ according to the first calculating value f_(Δθ1).

Additionally, in accordance with one embodiment, in step S5, thecalculating module 130 mixes the second sensing signal with the highfrequency carrier f_(c) to generate the second mixing signal m2, andlow-pass filters the second mixing signal m2 to acquire a secondcalculating value f_(Δθ2). Subsequently, the calculating module 130acquires the value of the cosine function of the operating angleaccording to the first calculating value f_(Δθ1), the second calculatingvalue f_(Δθ2), the first estimating angle, and the second estimatingangle {circumflex over (θ)}₂.

Moreover, in accordance with one embodiment, in step S5, the calculatingmodule 130 calculates the value of the operating angle φ through aninverse trigonometric function according to the values of the sinefunction and the cosine function of the operating angle φ. Subsequently,the calculating module 130 calculates the value of the rotor position θaccording to the operating angle φ, the quadrant of the operating angleφ, and the first estimating angle {circumflex over (θ)}₁.

It should be noted that details of steps S1-S7 can be ascertained byreferring to the exemplary embodiment mentioned above, and a descriptionin this regard will not be repeated herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims.

What is claimed is:
 1. An estimating method for a rotor position of amotor comprising: injecting a first high frequency signal to the motorat a first estimating angle; generating a first sensing signal of themotor in a period when the first high frequency signal is injected tothe motor; injecting a second high frequency signal to the motor at asecond estimating angle, wherein the second estimating angle isdifferent from the first estimating angle; generating a second sensingsignal of the motor in a period when the second high frequency signal isinjected to the motor; determining a quadrant of an operating angleaccording to the first sensing signal and the second sensing signal,wherein the operating angle is twice as large as an angle differencebetween the first estimating angle and the rotor position; and acquiringthe rotor position according to the first sensing signal, the secondsensing signal, and the quadrant of the operating angle.
 2. Theestimating method as claimed in claim 1, wherein the step of determiningthe quadrant of the operating angle according to the first sensingsignal and the second sensing signal comprises: acquiring a sinefunction of the operating angle and a cosine function of the operatingangle according to the first sensing signal and the second sensingsignal; and determining the quadrant of the operating angle according tothe sine function of the operating angle and the cosine function of theoperating angle.
 3. The estimating method as claimed in claim 2, whereinthe step of acquiring the sine function of the operating angle and thecosine function of the operating angle according to the first sensingsignal and the second sensing signal comprises: mixing the first sensingsignal and a high frequency carrier to generate a first mixing signal;low-pass filtering the first mixing signal to acquire a firstcalculating value; acquiring the sine function of the operating angleaccording to the first calculating value; mixing the second sensingsignal and the high frequency carrier to generate a second mixingsignal; low-pass filtering the second mixing signal to acquire a secondcalculating value; and acquiring the cosine function of the operatingangle according to the first calculating value, the second calculatingvalue, the first estimating angle, and the second estimating angle. 4.The estimating method as claimed in claim 2, wherein the step ofacquiring the rotor position comprises: calculating the operating anglethrough an inverse trigonometric function according to the sine functionof the operating angle and the cosine function of the operating angle;and calculating the rotor position according to the operating angle, thequadrant of the operating angle, and the first estimating angle.
 5. Theestimating method as claimed in claim 1 further comprising: determininga direction of a magnetic north pole of the rotor of the motor using apulse injection method.
 6. The estimating method as claimed in claim 1,wherein the step of injecting the first high frequency signal to themotor at the first estimating angle comprises: injecting the first highfrequency signal to at least one of a q-axis of the motor and a d-axisof the motor at the first estimating angle; and the step of injectingthe second high frequency signal to the motor at the second estimatingangle comprises: injecting the second high frequency signal to at leastone of the q-axis of the motor and the d-axis of the motor at the secondestimating angle.
 7. The estimating method as claimed in claim 1,wherein the first sensing signal is at least one of a first responsecurrent on a d-axis of the motor and a second response current on aq-axis of the motor, and the second sensing signal is at least one of athird response current on the d-axis of the motor and a fourth responsecurrent on the q-axis of the motor.
 8. An estimating device forestimating a rotor position of a motor, wherein the estimating device iselectrically connected to the motor, the estimating device comprising: ahigh frequency signal injection module configured to inject a first highfrequency signal to the motor at a first estimating angle, and inject asecond high frequency signal to the motor at a second estimating angle,wherein the second estimating angle is different from the firstestimating angle; a sensing module configured to generate a firstsensing signal of the motor in a period when the first high frequencysignal is injected to the motor, and generate a second sensing signal ofthe motor in a period when the second high frequency signal is injectedto the motor; and a calculating module configured to determine aquadrant of an operating angle according to the first sensing signal andthe second sensing signal, and acquire the rotor position according tothe first sensing signal, the second sensing signal, and the quadrant ofthe operating angle, wherein the operating angle is twice as large as anangle difference between the first estimating angle and the rotorposition.
 9. The estimating device as claimed in claim 8, wherein thecalculating module is further configured to acquire a sine function ofthe operating angle and a cosine function of the operating angleaccording to the first sensing signal and the second sensing signal, anddetermine the quadrant of the operating angle according to the sinefunction of the operating angle and the cosine function of the operatingangle.
 10. The estimating device as claimed in claim 9, wherein thecalculating module is further configured to mix the first sensing signaland a high frequency carrier to generate a first mixing signal, low-passfilter the first mixing signal to acquire a first calculating value, andacquire the sine function of the operating angle according to the firstcalculating value.
 11. The estimating device as claimed in claim 10,wherein the calculating module is further configured to mix the secondsensing signal and the high frequency carrier to generate a secondmixing signal, low-pass filter the second mixing signal to acquire asecond calculating value, and acquire the cosine function of theoperating angle according to the first calculating value, the secondcalculating value, the first estimating angle, and the second estimatingangle.
 12. The estimating device as claimed in claim 9, wherein thecalculating module is further configured to calculate the operatingangle through an inverse trigonometric function according to the sinefunction of the operating angle and the cosine function of the operatingangle, and calculate the rotor position according to the operatingangle, the quadrant of the operating angle, and the first estimatingangle.
 13. The estimating device as claimed in claim 8 furthercomprising: a determining module configured to determine a direction ofa magnetic north pole of the rotor of the motor using a pulse injectionmethod.
 14. The estimating device as claimed in claim 8, wherein thehigh frequency signal injection module is further configured to injectthe first high frequency signal to at least one of a q-axis of the motorand a d-axis of the motor at the first estimating angle, and inject thesecond high frequency signal to at least one of the q-axis of the motorand the d-axis of the motor at the second estimating angle.
 15. Theestimating device as claimed in claim 8, wherein the first sensingsignal is at least one of a first response current on a d-axis of themotor and a second response current on a q-axis of the motor, and thesecond sensing signal is at least one of a third response current on thed-axis of the motor and a fourth response current on the q-axis of themotor.